contrib/boost: disable extensive build log

Building boost prints the full list of files copied.
There are more than 20 000 of them, which pollutes logs.

Disable boost build logs, developers working on boost contrib
packaging can still re-enable logs if they need to.

Change-Id: I205297ed091bf0a5540e47f23ce4b7be3ad1a296

contrib/src/boost/rules.mak

@@ -7,6 +7,7 @@ PKGS += boost
 
 BOOST_B2_OPTS := variant=release \
 				 link=static \
+				 -d0 \
 				 --prefix="$(PREFIX)" \
 				 --includedir="$(PREFIX)/include" \
 				 --libdir="$(PREFIX)/lib" \